Toshiaki Sakurai

Numerical Analysis Method for Homologous Deformation Problem Using the Topology Optimization Technique Based on the Homogenization Theory.

The purpose of this study is to develop a topology optimization method to get a given detormation mode, such as a homologous structure. A minimization problem of a square error in relation to a given deformation and an active deformation is formulated for a linear elastic structure. To solve this problem the homogenized elastic constants are employed and a topology optimization is replaced with an optimal density distribution problem. using the similar method proposed by Bendsoe and Kikuchi. The homogenized elastic constants are calculated by the homogenization method for a microstructure having a rectangular hole. Using this method, a structural deformation is controlled to a given deformation. Simple examples are presented to confirm the validity of this optimization method.

Multiobjective Shape Optimization of Linear Elastic Structures Considering Multiple Loading Conditions. Dealing with Mean Compliance Minimization Problems.

This paper describes a numerical analysis method for multiobjective shape optimization problems of linear elastic structures. For an example, we treat a multiloading mean compliance minimization problem with a volume constraint. The presented method is based on the traction method that was proposed as a solution to the domain optimization problems by one of the authors. The traction method is implemented to analyze the speed field, which represents the domain variation, with regard to the deformation field of the linear elastic continuum formed in the objective domain applying the force in proportion to the shape gradient function. To scalarize the multiobjective functionals we employ the weighted lp-norm method with four types of norms. The shape gradient functions for each scalarized objective functional are obtained using the Lagrange multiplier method. For the numerical analyses we used a general-purpose finite-element code. Numerical results to a multiply connected plate problem and to a solid structure problem under the multiloading conditions show the validity of the present method to obtain practical Pareto solutions.

The stiffness of automobile outer panels

This paper presents an application of the finite element method (fem) to early stages of vehicle development for calculating larger deflections of body sheet panel. The stiffness of sheet metal shells is defined in conjunction with the local elastic buckling instability under concentrated loads. Considerable weight reduction of outer panels could be obtained by optimizing metal gauges, radii, peripheral conditions and the reinforcement of the panel. A roof panel is used as an example and its stiffness is calculated by fem analysis. The results show satisfactory correlation with the experimental ones. In the calculation procedure, central processor unit (cpu) time for finite elements was found to be reduced by varying and optimizing supporting conditions of the panel. The use of the stiffness analysis program during the initial design stages of a vehicle is described (a).